Measure your waist and times by 1.5. So if your waist is 32" your measurement with be 48". That is the width of your dress/skirt.
Determine how long you want your dress and that with be the length.
Using a gathering stitch on the top edge of your dress. Pull your gather to the width of your waist (32"). This was so easy using the spandex/knit I got on clearance at Joann Fabrics. Then using a zig-zag stitch go over your gather so they don't move.
Sew up your side seam using a zig-zag stitch
Cut out a piece of fabric that is the width of your waist (32") and how ever long you want the top section to be. The longer you make it the more if can fold but can also get bunchy. I made mine about 12 inches.
Attach the wrong side of the skirt section to the right side of the top section using a zig-zag stitch. I know that seems a little wonky, but when you put it on the top part will then fold over.
I then cut a piece of material that I could easily wrap around myself two time and have length to tie.
Sew the strip of material to the middle of your top section.
If you used a knit like I did then you are done - no seams to finish!!